The invention relates to the field of structural cables used in construction. It applies, in particular, to the anchorage of stay cables or prestressing cables.
Such structural cables are often made of a plurality of parallel tendons, such as strands for example. Their ends are anchored by means of blocks having throughholes where the tendons are individually blocked, for example by means of split frusto-conical jaws. The tendons have excess lengths extending beyond the anchorage blocks, which makes it possible to hold onto them when tensioning and anchoring the cable. It is common to retain this excess length so that the cable can be slackened at a later time.
As an example, this excess length may be 3 millimeters per meter of cable. For very long cables (several hundred meters for example), the excess length can become fairly cumbersome.
A constant concern of those who work with such structural cables is protecting the metal of the tendons against corrosion. Various anticorrosion techniques are used to protect the main portion of the cable and the portion in the anchorages (for example see WO 01/20098 A1).
In general, the metal of the tendons is exposed in the anchorage area. A cover is placed over the excess length of the tendons which extend beyond the front side of the anchorage system, and inside this cover a filling product is injected such as wax, grease, a polymer, a resin, or cement grout. The length of the cover must be greater than the excess lengths of the tendons extending beyond the anchorage system. The cover is therefore voluminous in the case of relatively long cables.
The space required by the arrangement on the front side of the anchorage can be problematic in certain configurations. By way of example of such a configuration, the stay cable anchorages on the pylons of cable-stayed bridges can be mentioned. The stays 12 generally form webs of inclined cables on each side of the pylon 14, as illustrated in FIG. 1. When the anchorages 15 are opposite one another in the pylon 14, the space occupied by the covers may interfere geometrically, as can be seen in the case of the covers 16 indicated by dotted lines in FIG. 2.
One solution to this problem consists of making covers that are curved in shape. However, this is not a satisfactory solution. The energy necessary to curve the bundle of tendons and maintain them in this position is very high. The attachments for the cover must then be particularly robust. Any maintenance operation which involves opening the cover becomes more difficult. In addition, a curved cover may make it impossible to position the jack used to manipulate the cable tendons.
A need therefore exists for a protection for the excess lengths of the tendons of an anchored cable, which limits the occurrence of the above space requirement problems.